In the long geological evolution, intact rock has been subjected to various structural geological actions, resulting in all kinds of weak structural planes. Moreover, these weak structural planes greatly reduce the strength of the rock, even directly affecting the stability of the whole underground caverns. Therefore, how to obtain a rock sample representing the basic physical and mechanical characteristics of the rock mass for lab tests so that related tests for the rock sample can be conducted is a problem to be solved.
At present, rock samples used for lab tests are mainly intact rock, and few lab tests are carried out for the rock mass. Even if tests of the rock mass with cracks are conducted, the tests are restricted to only a single or two discrete cracks and are limited to the rock mass of a small scale. There is currently no way to get a large scale rock mass comprising integral fracture network; this results in little understanding of the physical and mechanical properties of the rock mass and a lack of direct testing information for evaluating the overall stability of excavated cavern in jointed rock mass.